pH dropped

[stephish]

The pH in my 22 cube has been at 8.3 and when I checked it this afternoon was at 8.0. I have buffered it back up but am curious as to what would make it drop that much in less than 24 hrs.
my params have been until today
ammonia, nitrates, nitrites 0
Today they are
ammonia 0
Nitrites 0.25
Nitrates less than 5
sg 1.025
I haven't shown any ammonia but I think the nitrites are due to the urchin dying Sunday night/Monday morning.

 

[bonebrake]

It was probably just a fluke or due to some acidic matter from the dead urchin.
A range of pH from 8.0 to 8.6 is appropriate and as much as a 0.4 fluctuation throughout the day is acceptable. Most tanks have the lowest pH moments before the lights come on in the morning and the highest pH as soon as the lights go off at night due the differing concentrations of carbon dioxide.
:joy: